On my 3 rail layout, when the Z4000 voltage is set at 18 volts, the track voltage using the DTV function on the remote usually displays a track voltage of about 16.4 to 16.7 volts AC, and I can confirm this with a digital voltmeter.
On my 2 rail layout, when I set the power supply so that the measured voltage on the track at 18 Volts DC for operating MTH DCS engines, the handheld says that the track voltage is about 23.7 volts.
I think that this might be a software error (I use V4.20 on the 2 rail layout). I recall seeing it mentioned on a Forum. Does anyone know if in fact this is an error and, if so, has it been corrected with a later software release?